[{"id":73,"title":"Extragalactic radio sources as lighthouses for SETI","sha":"be48a68df1c2b616f413017a9138c386","user_id":62,"state":"published","body":"The search for extraterrestrial intelligence (SETI) is one of the most ambitious scientific endeavors. It aims at detecting signals produced intentionally or unintentionally by extraterrestrial civilizations ([Siemion et al., 2013](http://arxiv.org/abs/1412.4867)). The Galaxy, however, is vast and finding suitable telescope targets for SETI is a critical task ([Turnbull \u0026 Tarter, 2003](http://iopscience.iop.org/0067-0049/145/1/181)).\r\n\r\nWe examine a strategy for selecting target areas for (active and passive) SETI aimed at improving chances for success.  The aim is to search for and/or send electromagnetic signals towards and/or from notable extragalactic radio sources.  Assuming that astronomy-wise civilizations are also involved in frequent multi-wavelength monitoring of conspicuous radio sources, the probability for interstellar observers to detect each other when observing in the same direction is increased. A similar idea was proposed by [Lemarchand (1995)](http://link.springer.com/article/10.1007/BF00982337) using Supernova 1987A.  However, radio sources are constant \"lighthouses\" and exist all across the sky.\r\n\r\nFor illustration purposes, we calculate that a signal emitted in a ~1 degree beam in the opposite direction of Centaurus A, could reach ~200 stars, mostly M-dwarfs, at distances \u003c600pc (stellar density model by [Gould et al., 1996](http://iopscience.iop.org/0004-637X/482/2/913)). Conversely if we search for ETI signals around Centaurus A, using the Allen-array (PFOV ~3 degrees, [Deboer et al., 2006](http://link.springer.com/article/10.1007/s10686-005-4193-3)), ~200 stars at distances \u003c300pc will be included in the field and the chance of detecting a message from a civilization using this strategy, is large.","created_at":"2015-02-20T00:46:47.737Z","updated_at":"2018-02-18T07:02:57.524Z","zenodo_id":23173,"doi":"http://dx.doi.org/10.5281/zenodo.15539","subject":null,"tags":["seti","astronomy","astrobiology"],"vote_count":8,"view_count":1,"score":8.1,"deleted":false,"muted":false,"tweeted":true,"attachment_file_name":null,"attachment_content_type":null,"attachment_file_size":null,"attachment_updated_at":null}]